Thread trimmer for buttonhole sewing machines



Sept. 26, 1933. .y 1 H, P|KUL 1,927,950

THREAD TRIMMER FOR BUTTONHOLE SEWING MACHINES Filed Jan. 6, 1932 5SheetS-Sheet l Figi lrwenor. doseph H. PKUl Sept. 26, 1933. 1 H P|KU|1,927,950

THREAD TRIMMER FOR BUTTONHOLE SEWING MACHINES Filed Jan. 6, 1932 v 5Sheets-Sheet 2 Fig@ 4d 'as so 28 se l n e n To T. Joseph H. Pi Kul Sept.26, 1933. J, plKUL 1,927,950

THREAD TRIMMER FOR BUTTONHOLE SEWING MACHINES Filed Jan. 6, 1952 5Sheets-Sheet 3 Sept. 26, 1933. J, P|KUL 1,927,950

THREAD TRIMMER FOR BUTTONHOLE SEWING MACHINES Filed Jan. 6, 1932 5Sheets-Sheet 4 Figli lnven'o'. Joseph H. PKUl bymaaMk/@M Sept. 26, 1933.J. H. PIKUL.

THREAD TRIMMER FOR BUTTONHOLE SEWING MACHINES 5 Sheets-Sheet 5 FiledJan. 6, 1952 Fglfs lnvenl'o'r. Ljoseph H. Pi Ku bymmy M AX Tys.

Patented Sept. 26, 1933 UNITED STATES 'PAT Josephv H. Pikul, Troy, N.Y., assigner tov'lfhev Reece Button Hole Machine Company, Boston,

Mass., a corporation Application January 6,

19 Claims.

This invention relates to thread-trimming devices for buttonhole sewingmachines by which the under thread and the stay cord, if one is used,are cut close to the work at the completion of the buttonhole, and itrelates particularly to that class of thread-cutting devices in whichthe thread is cut after the work clamps have been opened.

An object of the invention is to provide a thread trimmer of this typewhich is relatively simple in its construction and which will operate totrim the thread close to the work even though the Work is not held bythe operator, and which will also operate to as effectively trim thethread when the sewing is being done on slazy fabric as when thebuttonhole is being sewed in a thicker and relatively llrm fabric.

In carrying out my invention I propose to employ a thread-cuttingmechanism whose upper surface is substantially flush with thework-supporting surface of the Work-holding means. I also propose toemploy a thread-cutting mechanism including a cutting member, thecutting edge of which lies close to the surface of the work and acrosswhich the thread is extended after the sewing is finished.

In the construction herein shown the threadcutting mechanism includes athread-cutting member which forms part of the work-supporting surfaceagainst which the work is clamped by the work clamps so that during thesewing on the buttonhole said thread-cutting member forms part of theWork-clamping means. The upper surface of such cutting member is thusflush with the Work-supporting surface of the work-clamping means.

After the sewing on the buttonhole has been completed and the clampshave been opened the thread-cutting member is given its operativethread-cutting movement by which the under n thread and stay cord arecut close to the Work.

Buttonhole sewing machines are usually constructed so that after thesewing on the buttonhole has been completed the stitch-forming mechanismand work-holding means have a relative movement to carry the parts fromstitching to buttonhole-cutting position and during such relativemovement a length of under thread and stay cord is drawn out through thesewing opening of the throat plate, which length extends at an angle tothe work.

In one embodiment of my invention the threadcutting mechanism isprovided with a cutting blade having a cutting edge which extendsnormally in a direction transverse to said relative ofk Maine Y n 193.2.serial Ne. 585,073v

(c1. i12-252) l I y v movement, seid blade being 'sol positionedi thatat the end of the relative movement the blade will be positioned betweenthe throat plate and the work and the thread leading from the Work ENT.OFFICE 7 to the throat plate `will be drawn across said cutting edge. e

After the parts have been thuscarried into buttonhole-cutting positionand the clamps have been released the thread `trimmer is actuated totrim the thread and because of the fact that the thread is Adrawnacrossthe cutting edge of hole sewing machine embodying my improvements;I

- Fig. 2 is a top plan view of the work-holding means with part brokenout and illustrating one form of the thread cutter; e

' Fig. 3 is a section on the line 3 3, Fig. 2;

Fig. 4 is a perspective view of the thread-cutting member which formspart of the work-supporting surface;

Fig. 5 is a view of the element which co-operates with thethread-cutting member shown in Fig. 4;

Fig. 6 is an under side View of the clamp plate shown in Fig. 2; Y

Fig. 7 is a plan view of the turret with the loopers and othervmechanism omitted but showing the means by which the rotation oftheturret actuates the thread cutter;

Fig. 8 is a section on the line 8-8, Fig. 2;

Fig.9 is a View of the thread trimmer showing its manner of operation;

Fig. 10 is a fragmentary sectional view showing the position of thepartsjust before the thread trimmer is actuated.

Fig. 11 is e view similar to Fig. l2 but showing showing the means foroperating the thread cutter illustrated in Fig. 11. v

The sewing machine shown in Fig. 11 is of that type which comprises abed frame 1 carrying the work-holding means by which the work 2 is heldvduring the sewing operation, anda-lso the stitch frame 3 mounted on thebed 1 and carrying the stitch-forming mechanism. The stitch- .formingmechanism comprises the usual needle 4 operating from above the work andmounted in a reciprocating needle bar 5 and under thread mechanismVwhich may conveniently be in the form of oscillating loopers andlooperspreaders (not shown) that are carried by a turret 6 rotatively mountedin the portion 7 of the stitch frame 3 which is located below the bedframe 1 and provided with the usualthroat plate 27.

The work-holding means comprises work-supporting surfaces situated onopposite sides of the buttonhole slit and workw'clampsv for clamping thework against thework-supporting surfaces. The Vwork-supporting surfacesare carried by clamp plates 8 and 9 Whichform between them an opening 26Ithrough which the needle operates. The work clamps by which the work isclamped against the work-supporting surfaces are indicated at 10 and 11and said clamps are carried as usual by the arms 12 which are pivotallymounted'on the clamp plates 8 and 9.

The work-supporting surface on the clamp plate 8 which is situated atone side of thevbuttonhole slit andagainst which the work clamp 10clamps the work is constituted by the matrmember 13 `which has the usualroughened surface.

" The work-supporting surface on the other side of the buttonhole slitwhich is rcarried by the 'clamp plate 9, and against which the workclamp 11 clamps the work, is formed partially by a mat I member 14, andpartially by a thread-cutting horizontal plane or about a vertical axis.

member, the upper surface of which is flush with the work-supportingsurface 14.- In the construction shown in Fig'. 2 this threadcuttingmember is indicated at 15 and it is pivotally mounted in the clamp plate9 vto swing in a For this purpose the member 15 is mounted to turn on astud 16 which is mounted in the clamp `plate 9. The upper surface of thethread-cutting member 1511s flush with the surface of the mat member 14and the end of'said member which is adjacent the mat member 14 underliesthe work clamp 11 vas best seen in Fig. 2 wherein the complete shape ofthe'work clamp 11 is indicated in dottedrlines. f

The cutting member 15. is provided with a thread-cutting edge 17 whichpreferably has an inclined position with relation to the length of thebuttonhole. The end edge 18 of the cutting member 15 is formed on an arcstruck from the pivot 16 as a center and the adjacent edge 19 of the matmember 14 is lsimilarly curved.

When thev clamps 10, 11 are closed the'clamp v 10 will clamp the workagainst the mat 13 while the clamp 11 iwill clamp the work against boththe mat 14 .and the end'of the cutting member 15.

This thread-cutting member 15, Ywhich thus forms part ofthe surfaceagainst which the work is clamped during the sewing operation and whichthus constitutes a work-supporting cutting member; co-operates withanother cutting'member 20 to effect the cutting of the thread. Themember the cutter member 15 and the upper surface of the member 20.

' As will be understood by those vfamiliar with buttonhole sewingmachines of this type the stitchorming mechanism and work-holding meanshave a relative movement after the sewing on the buttonhole has'beencompleted and the stitch-forming mechanism has come to rest withtheneedle raised, such relative movement carrying the parts from stitchingtoy buttonhole-v cutting position. During this relative movementy underthread mechanism and during this fulk ther relative movement theincreased strain which is put on theupper thread will break it asdescribed in my co-pending application Serial Nc. 525,092, filedMarch25,1931. This leaves the under thread and stay cord to be cut.`

rlhe cutting portion 23 and cutting edgev24 of the member 2) are sosituated that during such relative movement the portion 23 is placedbetween the throat plate 27 ,and the work so that at the end of suchrelative movement the.por' tien 23 of the cutting member2 will besituated between the workvand the lengths land 71 of the under threadand stay cord which have been drawn through the throat plateas best seenin Fig. 10. During such movement also theunder thread and stayccrd Will'be drawnagains Vor across the cutting edge24 of the cutting memn ber 20so that at this time these threads to be cut will be located betweenthetwo cutting' edges 17 and 24. v f

This operation of introducing the blade mem" ber between the throatplate and the workv and thus placing said memberbetween the work and thelengths 70 and 710i the under thread and stay cord which have been'drawnthrough the buttonhole and in a position so lthat said thread and staycord will be drawn across the cutting edge ofthe cutting member is madepossible because of the fact that said cutting edge extends-transversely to the direction of relative movement between thestitch-forming mechanismand Work-holding means by which the` partsk arecarried from stitching to buttonhole-cutting position.

After the thread and stay cord have been placed across the cutting edge24" the cutting members 15 and` 20 are actuated to cut the thread bybeing turned about their common Vpivot thereby closing the cutting edgestogether with a scissorsflike action. Before this Vis done, however, thewerk clamps arev released. so that the cutting of the under thread andstay cord occurs while the work yis unclamped. v

InA the construction shown in Fig. 2 the threadvcutting movementinvolvesa movement of both the cutting edges 17 and 24, these edgesmoving toward each other and having ascissors-iike action. Since thework is resting on the two Vbladesor cutting members 15 and 2G and sincethe blade 20 is relatively thin the stay cord and under thread will becut close `tothe work. Moreover, since eachcutting edge has a movementVtoward the, other cutting edge there will be no tendency to displacethework. Any Yfrictionof one cuttingmember against the under surface ofVthe work tending to move it in' one direction is rec counteracted bythe movement of the other cutting member against thework tending to moveit in the opposite direction and hence the work will be held stationaryand the threads will be properly cut even though the operator is notholding the work, it being understood that the Work is unclamped duringthe thread-cutting operation. Moreovenvsince both cutting edges 17 and24 are inclined to the center line of the buttonhcle the thread cutterwill work equally well regardless of the length of the buttonhole.

In the construction shown in Fig. 2 I propose to make use of the turningmotion of the turret 6 to give the cutters 15 and 20 theirthread-cuttingmovement.

It will be understood by those familiar with buttonhole sewing machinesof this type that the turret 6 makes a half revolution in sewing aroundthe eye end of the buttonhole and after the sewing on the buttonhole hasbeen completed and while the parts are moving, or after they have moved,from stitching to buttonholecutting position, the turret will have a.reverse rotation to bring it back to its normal position. Theconstruction shown inFigs. 2 to 8 is such that this reverse rotation ofthe turret serves to actuate the cutters 15 and 20.

The cutter element 15 has a tail portion 28 and the cutter element 20has a complemental tail 29. When the cutter elements are assembled thesetails 28 and 29 are spaced from each other and situated between them isa cam member 30 which is fast on the upper end of a stud 31 that isrotatively mounted in the work clamp 9. This stud is shown as extendingthrough the work clamp 9 and also through a plate 37 Which is situatedunderneath the clamp plate 9 and is secured thereto by a screw 38. Thestud 31 is shown as having a collar 39 located between the clamp plate 9and the plate 37, by which construction the stud will be held fromvertical movement. This stud has an arm 32 projecting therefrom which isprovided with a depending extension 33. The turret 6 has an arm 34 rigidtherewith which extends radially beyond the turret and is provided Withan upstanding dog portion 35. The arm 34 is so positioned on the turretthat when the sewing on the buttonhole has been completed but before theturret begins its reverse rotative movement the upstanding dog 35 willhave'a position closely adjacent the downturned extension 33 of the arm32 as indicated in Figs. 7 and 8. When the reverse turning movement ofthe turret takes place in the direction of the arrow Fig. 7 the dog 35will engage the down-turned end 33 of the arm 32 thereby swinging saidarm and turning the'stud 31 and the cam member 30 as shown in Fig. 9.This turning movement of the cam member separates the tails 28 and 29thereby causing the cutting edges 17 and 24 to close together, whichoperation will cut the under thread and stay cord as above stated.

It will be noted from Fig. 9 that the cam 30 acts on the tail 29 of thecutting member 20 adjacent the end of the tail while it acts on the tail28 of the cutting member 15 at a point relatively close to the axis ofrotation. As a result the cutting member 15 will be given a greaterturning movement than the cutting member 20 and hence while both cuttingedges 24 and 17 move toward each other yet during the entire movement ofthe cutting member 24 it will maintain a position intersecting thecenter line of the buttonhole and hence will be in-a. position to engagethe under thread and staycord regardless` of the length of the buttonhole being sewe'd. Y

36 indicates a spring which acts on the tail members 28and 29 and tendsnormally to hold them in the position shown in Fig. 2. This springserves to open the scissors cutter and to 4'restore it to normalposition after the cutting operation. A40 indicatesr a cover plate whichoverlies and covers up the tail portions of the cutters and the spring36. This cover plate has a recess 41 in one end which fits around thecircular body portion 21 of the cutter member 20, said cover platecoming flush with the body portion. This cover plate is held in positionby the screw 38above referred to.

The blades 15 and 20 of the scissors-like cutting device may be maderelatively vthin so that they take a small amount of room in a verticaldirection and as the top surface of the cutting member 15 is flush withthe top surface of the mats 13 and 14 the cutter occupies very littleroom and does not interfere at all with the sewing operations.

In' the construction shown in Figs. 11 and 12 there is a single movablecutting element, thisr being indicated at 42. Said cutting element isshown as pivotally mounted on a stud 43 carried by the clamp plate 9 andthe upper surface thereof is flush with the mat 14 and the end thereofconstitutes part of the surface against which the work 2 is clamped bythe work clamp 11. As shown in Fig. 11 the end of the cutting element 42underlies the clamp member 11 so that when the latter is in loweredclamping position it clamps the work against the end of the cutterelement 42 as well as against the mat 14. This cutting element 42 isprovided with a cutting edge 44 which co-operates with the front edge 45of a cover plate 46 to cut the thread and stay cord, the *edge acting asa ledger blade. In this embodiment the cutter v42 is given its operativethread-cutting movement by the turret-rotating means rather thandirectly by the turret.

The cutter member 42 extends beyond its pivotal mounting 43 as shown at47 and said projecting end is provided with a stud 48 which dependsthrough a slot 49 formed in the clamp plate 9. This stem is acted on bya spring 50 which normally tends to hold the cutter in its inoperativeposition shown in Fig.A 11 wherein it rests against the edge 51 of themat 14. This stud 48 is adapted to be acted on by a nger 81 extendingfrom a slidev 52 that is located beneath the bed frame 1 and is adaptedto move transversely thereof. The slide is provided at one end with aslot 53 through which extends a pin or stud 54 secured to the bed frame1 and the other end of the slide is pivotally connected to a lever 55pivoted at 56 to the bed frame and having at its free end a dog member57 adapted to be engaged by a nose 58 which is carried by theturret-rotating lever 59. Thislever 59 is such as is found in buttonholesewing machines of this The parts are shown-in Fig. 1l inthepositionthey assume when the stitching on the buttonhole is completed,and when the parts are moved fromv stitching to buttonhole cuttingposition,

the throat plate 27 will be moved into the dotted line position andduring this movement the plate i6 vwith its cutting edge 45 will beintroduced between the Ithroat plate and the workand the underthread andstaycord which` are drawn through Athe throat plate by'such movementwill be laid across the edge i5.l At this time the levers fifi 59 areoperated to give the turret its reverse movement Vand during vsuchmovement the nose 58 engages the dog 5'? and swings the lever clockwise,Fig. `i3 thereby moving the 'slide 52y to the right which will cause thenger 81 to engage the stud `48 and thereby give the cut ter i2 itsthread-cutting movement. Y

l During the swinging movement of the lever 59 vthe nose 58 will wipe byand become disengaged from the dog 57 Yand when this occurs the bar 52:will be returned to its normal position bythe spring 58 while thespring 50 will return the knife to its normal inoperative position. f

In the construction illustrated in Fig. 11 the plate 45 is the membervwhich is introduced between the throat plate and the worlby therelative movement from stitching to buttonhole-cutting .25.

position and the edge 45 is theedge which stands transverse to suchmovement and around which the stay cord and under thread are laid, Thisplate i6 also serves as themeans for supporting i the worlrandpreventing it from being pulled 3.0.

Y against both the stationary and movable por- 40,

tions of said workfsupporting surface, and'means operative after theclamps are released to move the movable portion of said surface thereby-to cut the thread beneath the Work. Y

2. In a buttonhole sewing machine, in'combination, work-holding meanscomprising a worksupporting surface Yand worlr` clamps for clamping thework against said surface, said worksupporting surface 'having a portionstationary relative to the work and another portion mova- ,50.

ble relative thereto and provided with a cutting edge, and meansoperative after the Yclamps are released to give the 'movable portion ofsaid sur-r face an' operative movement to cut the thread beneath theWork.

3. In a buttonhole sewing machine, in combination, work-holding meanscomprising clamp plates having work-clamping mats, a thread-cuttingmember adjacent one end of one mat and having its upper surface flushwith the worksupporting surface of the mat, work-clamping meansoperating to clamp the workr againstthe mats and thethread-cuttingmember, and means operative after the clamps are opened to give theVthread-cutting membera movement to cut the 5.l In a buttonhole sewingmachine of the type having stitch-forming mechanism including underthread mechanism and a turret on which theY kunder thread mechanism ismounted, the combi-` nationwth said stitch-forming mechanism and turret,of work-holding means,v a scissors-like thread cutting elementforcutting the thread at the end of the sewing operation, and meansforactuating the thread-cutting element by a rotary movement of theturret.

6'. In a buttonholeV sewing machine of the type having stitch-'formingmechanism including under thread mechanism and a rotary turret on whichthe under thread mechanism is mounted and Vwhich has a reverse rotationafter the completion of the sewing operation, the combination with saidturret, of work-holding means provided with a work-supporting surface, apivoted thread-cutting member forming part vof such work-supportingsurface, work-clamping means `to clamp the work against'thework-supporting surface including the thread-cutting member, and meansroperated by the reverse rotation of the turret after theclamping meansare released to actuate the thread-cutting member to cut the threadbeneath the work.

7. In a buttonhole sewing machine of the type having A stitch-formingmechanism including under thread mechanism and a rotary turret on whichthe under thread mechanism is mounted and which has a reverse rotationafter the completion ofthe sewing operation, the combination with saidturret, of work-holding means provided with a work-supporting surface, apair of pivotally-mounted thread-cutting members, one of which formspart of the Work-supporting surface, work-clamping means toclamp thework against said surface including said thread-cutting member, andmeans operated by the reverse turning movement of the turret to actuate,the thread-cutting elements after the clamps have been released. v

8. A buttonhole sewing machine having a work-supporting surface againstwhich the Work is clamped during the sewing operation, a pvotedcuttingblade forming part of such surface, workk clamps for clamping thework against said surface including said blade, said blade having acutting edge extending at an angle to the centerline of the buttonhole,a co-operating cuttingblade also having a cutting edge at an angle tothecenter line of the buttonhole but extending across said center line,and means operative after the work clamps are opened to actuate theblades to cut the thread beneath the work.

9. In a buttonhole sewing machine, in combination, a work-supportingsurface against which the work is clamped duringthe sewing operation,Work-clamping -means for clamping the Work against said work-supportingsurface, a threadcutting member whose upper surface is substantiallyilush with the work-supporting surface, and means operative after theclamps are released to actuate the cutter to cut the thread beneath thework.

10. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-holding means, said stitch-forming mechanism, andworkholding means having a relative movement at the end of the sewing atthe completion of which relative movement the thread leading to thesource of supply extends away from the plane of the work and a threadcutter having a cutting vedge which lies close to the surface of theWork and across which the thread is extended at the end of such relativemovement.

1l. In a buttonhole sewing machine, in combination, stitch-formingmechanism and workholding means having a relative movementl at the endof the sewing operation, a thread cutter having a cutting edge whichnormally extends transverse to such relative movement and across whichthe thread leading from the last stitch is laid by such relativemovement.

12. In a buttonhole sewing machine, in combination, stitch-formingmechanism, Work-holding means, a throat plate through which the threadis led to the work, said stitch-forming mechanism and work-holding meanshaving a relative movement at the completion of the sewing to carry theparts from stitching to buttonhole-cutting position and to draw out alength of thread through the throat plate, a thread cutter having acutting edge extending transverse to such relative movement and acrosswhich the thread drawn out from the throat plate is laid.

13. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-holding means, a throat plate through which thread isled to the work, said stitch-forming mechanism and work-holding meanshaving a relative movement at the completion of the sewing to carry theparts from stitching to buttonhole-cutting position and to draw out alength of thread through the throat plate, a thread cutter having acutting edge extending transverse to such relative movement and acrosswhich the thread drawn out from the throat plate is laid, such relativemovement placing the thread cutter between the throat plate and thework.

i 14. In a buttonhole sewing machine, the combination withstitch-forming mechanism, of means for trimming the thread and/ 0r staycord consisting of two movable co-operating cutting elements situatedsubstantially parallel with the plane of the work, and with one of suchelements extending transversely to the line of the buttonhole stitching.

15. In a buttonhole sewing machine, the combination with stitch-formingmechanism, of

means forA producing a relative movementv between the stitch-formingmechanism and the work, and a thread-trimming knife having a cuttingedge situated transversely to the line of stitching and which is placedbetween the thread and/ or cord to be trimmed and the Work by suchrelative movement.

16. In a buttonhole sewing machine, the combination with stitch-formingmechanism, of means for producing a relative movement between saidstitch-forming mechanism and the work, a thread-trimming knife having acutting edge extending transversely to the line of stitching, said knifebeing so positioned that it is placed between the work and the thread orcord to be trimmed by such relative movement.

17. In a buttonhole sewing machine, the combination with stitch-formingmechanism, of a trimming knife comprising a pair of blades havingcutting edges, and means for actuating the blades, the locus of theintersection of the cutting edges of the blades as the latter are closedmoving in a line substantially parallel to the plane of the work andtransverse to the line of stitching.

18. In a buttonhole sewing machine, the combination with stitch-formingmechanism, Work-clamping means4 comprising clamp plates against whichthe work is clamped and two movable co-operating thread-trimmingelements, one of which acts as a part of the work support, situated ontop of the clamp plates.

19. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-holding means, said stitch-forming mechanism andwork-holding means having a relative movement at the end of the sewing,at the completion of which relative movement the thread leading to thesource of supply extends away from the plane of the work, and a threadcutter having a cutting edge situated substantially parallel to theplane of the work and which lies close to the surface of the work andacross which the thread is extended at the end of such relativemovement.

JOSEPH H. PIKUL.

vso

ofl

ifi@

